In the absence of profile modification, water injected into the reservoir will go into the high-permeability zones and will bypass the oil-saturated, low-permeability zones. This paper presents the laboratory evaluation of a water-soluble relative permeability modifier (RPM), a hydrophobically modified polymer that was developed initially for water control in production wells. By injecting the RPM within the high-permeability zones, injected water will be diverted into low-permeability zones to improve the sweep efficiency of the waterflooding project.
The polymer functions by adsorption onto rock surfaces and effectively reduces water flow with little or no damage to hydrocarbon flow. The treatments are extremely easy to mix and pump and require no postjob shut-in time. This RPM was evaluated in 5-ft and 10-ft sandpacks to investigate the following parameters: (a) depth of penetration, (b) diversion properties (c) injection rate, and (c) polymer concentration. High-permeability (~2000–1500 mD) and low-permeability (~250–150 mD) sandpacks were evaluated as porous media. Based on this laboratory evaluation, this RPM can effectively penetrate through a 10-ft sandpack providing permeability reduction to water throughout the length of the porous media. In addition, excellent diverting properties were observed while bullheading the treatment in sandpacks in parallel with significant permeability contrast.